With regard to the second part of the question (other chemicals in the future).
Volatile organic compound has many definitions depending on context.
Perhaps your question is related to a regulatory issue. Usually when the question comes up it is in regard to EPA Hazardous Air Pollutants (HAPs) regulations. Frequently the answer is a functional definition (does a sample exhibit the characteristic as defined in a standard method). EPA Method 24 is an example of such a method. When a regulation says determine if a product contains VOCs by EPA Method 24 it means just that (run the test on it).
Alternatively, your question could be one of decision regarding an appropriate analytical method. Specifically, a purge and trap method vs an extraction method. A good rule of thumb here is vapor pressure. Naphthalene is analyzed by both methods and is a good marker for a vapor pressure breakpoint for the two methods.
Anyway, I would need to know more about the context of the question to help more.
good luck